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Convert WebM to MP4

Choose a playback preset, convert your WebM, and download the finished MP4 video.

InputMP4, WebM, MOV and M4V videoOutputMP4

WebM is excellent on the web and awkward everywhere else: send one to a phone, a TV, a client or an editing app and it may simply refuse to open. Converting to MP4 with H.264 and AAC produces the file that plays on everything, and this tool lets you pick a playback preset and check the result before downloading.

Why MP4 is the compatibility format

H.264 has been the default video codec for well over a decade, which means hardware decoders exist in essentially every phone, tablet, laptop, TV and console shipped in that time. That has two consequences: the file plays, and it plays without draining the battery, because decoding happens in dedicated silicon rather than on the CPU. WebM in VP9 has software support in browsers but far less hardware support outside them, which is exactly why a WebM that streams perfectly on a website can stutter or fail when opened directly on a TV.

What the conversion costs

This is a full re-encode: VP9 or VP8 cannot be repackaged as H.264, so the picture is decoded and encoded again, with some generational loss. Choosing a higher quality preset keeps it invisible. Expect the MP4 to be somewhat larger than the WebM at comparable quality, since H.264 is less efficient than VP9 — that is the price of universal playback. One thing that does not survive: if the WebM had a transparent background, the alpha channel is lost, because MP4 has nowhere to put it.

Questions, answered

Why won’t my WebM play on my phone or TV?

Because WebM support outside browsers is patchy. Many phones, TVs, messaging apps and editors handle only MP4. Converting to H.264 MP4 makes the file play everywhere.

Will the MP4 be bigger than the WebM?

Usually a little, because H.264 is less efficient than VP9 at the same quality. That is the trade-off for playing on every device.

Does converting lose quality?

Some, since the video is fully re-encoded rather than repackaged. A higher quality preset keeps the loss invisible in normal viewing.

What happens to a transparent WebM?

The transparency is lost — MP4 has no alpha channel, so transparent areas become solid. Keep the WebM if you still need the alpha version.

Which preset should I pick?

A standard H.264/AAC preset suits almost everything. Choose a more conservative one if the file is going to older hardware, which can be picky about profile and level.

Useful next steps

Continue with a tool that fits naturally after webm to mp4.

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